So is this a sign that there’s an engagement announcement coming? Myka Meier, the founder and director of Beaumont Etiquette and the expert on all things proper in the royal family, thinks so.

“I believe an engagement is imminent,” she tells PEOPLE. “I think to show PDA at such a highly publicized public event would be a very conscious decision by Prince Harry, and shows the seriousness of the relationship. Meghan would very much have taken his lead under the circumstances.”

And while Meier admits that there is “no formal protocol” against showing PDA at events, it is rare to see an unmarried royal get affectionate at official events.

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“It certainly makes a statement,” says Meier. “To show PDA as a representative of the British monarchy at such an official event says everything! Rarely in the past have we seen unmarried royals showing PDA with significant others at a public event — it’s a sure sign that things are as serious as they could be without being engaged.”

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The Invictus Games — which Harry launched in 2014 and serves as a Paralymic-style international event for wounded servicemen and women —was also the perfect place for the pair to go public, as Meier notes.

“It feels quite natural for [their outing] to be in the city that Megan lives and where their relationship blossomed,” says Meier. (Markle lives in Toronto and films Suits in the city.) “It’s also a cause near and dear to Prince Harry’s heart, and to have Meghan there to show her support in such a public way is telling.”

This wasn’t the first time Markle was spotted at the games. On Saturday, the American actress attended the opening ceremony alongside her longtime friend Markus Anderson — who reportedly introduced her to Harry. However, the outing wasn’t exactly a romantic date as Markle sat over 12 seats away from Harry, who was seated next to First Lady Melania Trump and other foreign officials.